Decorative sheets used on window panes of shops, for example, are required to be easy to attach even for non-contractors, without trapping air. Even after failed attempts to fix them, these decorative sheets need to be easily reattachable.
In particular, decorative sheets used for advertisement, for example, need to be replaced after short time cycles. In that case, they should be easily peelable even after having been attached for a predetermined period of time.
Thus, silicone pressure-sensitive adhesives, which can cope with these requirements, have started to be used instead of conventional acrylic pressure-sensitive adhesives (see, for example, Patent Document 1).
That is, Patent Document 1 discloses a decorative fixed sheet in which an adhesion layer (pressure-sensitive adhesive layer) is provided on one surface of a substrate film. The adhesion layer is formed by crosslinking at least one silicone selected from a silicone composed of a linear polyorganosiloxane having vinyl groups only at the two molecular ends, and a silicone composed of a linear polyorganosiloxane having vinyl groups at the two molecular ends and side chains. An image-receiving layer (print-receiving layer) is provided on the other surface of the substrate film.
On the other hand, for example in the case of decorative sheets that are made for indoor applications on window panes of apparel-related shops, external light enters through the pressure-sensitive adhesive layer side. Consequently, in order to prevent external light-induced deterioration of the print-receiving layer, an ultraviolet absorber has to be incorporated into the pressure-sensitive adhesive.
Thus, silicone-based pressure-sensitive adhesives having a predetermined ultraviolet absorber incorporated therein have been suggested (see, for example, Patent Documents 2 and 3).
That is, Patent Document 2 relates to an invention of a polymeric ultraviolet absorber intended to be incorporated mainly into a silicone-based resin. The patent document discloses a silicone-containing polymeric ultraviolet absorber, which is a polymerization product based on (A) at least one ultraviolet-absorbing monomer selected from a benzophenone-based ultraviolet-absorbing monomer represented by the following Formula (1) and a benzotriazole-based ultraviolet-absorbing monomer represented by the following Formula (2); (B) silicone macromer represented by the following Formula (3); (C) a functional group-containing copolymerizable vinyl monomer; and (D) a functional group-containing copolymerizable vinyl monomer, the polymeric ultraviolet absorber having a weight average molecular weight of 10,000 to 100,000.

wherein in Formula (1), R11 represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms; R12 represents an alkylene group having 1 to 10 carbon atoms, or an oxyalkeylene group having 1 to 10 carbon atoms; m1 represents 0 or 1; R13 represents a hydrogen atom, or a lower alkyl group; and X1 represents an ester bond, an amide bond, an ether bend, or a urethane bond; and

wherein in Formula (2), represents a hydrogen atom, a halogen atom, or a methyl group; R22 represents a hydrogen atom, or a hydrocarbon group having 1 to 6 carbon atoms; R23 represents an alkylene group having 1 to 10 carbon atoms, or an oxyalkylene group having 1 to 10 carbon atoms; m21 represents 0 or 1; R24 represents an alkylene group having 1 to 8 carbon atoms, an alkylene group having an amino group and 1 to 8 carbon atoms, or an alkylene group having a hydroxyl: group and 1 to 8 carbon atoms; m22 represents 0 or 1; R25 represents a hydrogen atom or a lower alkyl group; and X2 represents an ester bond, an amide bond, an ether bond, or a urethane bond; and

wherein in Formula (3), R31 represents a hydrogen atom or a methyl group; R32 represents an alkylene group having 1 to 6 carbon atoms, or an oxyalkylene group having 1 to 6 carbon atoms; m31 represents 0 or 1; R33 represents an alkylene group having 1 to 6 carbon atoms, an alkylene group having an amino group and 1 to 6 carbon atoms, or an alkylene group having a hydroxyl group and 1 to 6 carbon atoms, m32 represents 0 or 1; and n represents an integer from 1 to 200.
Furthermore, Patent Document 3 discloses, as a pressure-sensitive adhesive composition applicable to decorative sheets or the like, a silicone-based re-adherable pressure-sensitive; adhesive composition containing an organopolysiloxane resin-organopolysiloxane reaction product (A), which is formed by subjecting the following component (a1) and component (a2) to a condensation reaction in the presence of component (a3):
(a1) 100 parts by weight of an organopolysiloxane resin essentially composed of a R13SiO1/2 unit (wherein R1's each independently represent a hydroxyl group, an alkoxy group having 1 to 8 carbon atoms, or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms) and a SiO4/2 unit, in which the molar ratio of the R13SiO1/2 unit with respect to the SiO4/2 unit is 0.6 to 1.0, and the content of the hydroxyl group or the alkoxy group is within the range of 0.3% to 2.0% by weight;
(a2) 20 parts to 150 parts by weight of a linear or branched diorganopolysiloxane having at least one hydroxyl group or an alkoxy group having 1 to 6 carbon atoms in one molecule, and having an average degree of polymerization of 100 to 1,000; and
(a3) a condensation reaction catalyst.
Furthermore, Patent Document 3 is described to the effect that a benzophenone-based ultraviolet absorber and the like can be incorporated as an ultraviolet absorber into the composition.